The technology relating to the reproduction of documents has consistently advanced over time. At present, the traditional light lens copier utilizes xerographic means to automatically reproduce large quantities of stacked paper at a rate of over 100 pages per minute. Current printing technology, at comparable speeds, employs raster output scanning means to output a stored image, in digital form, onto a recording medium by way of various marking technologies, e.g. by electrostatographic reproduction or inkjet printing. Scanning technology, as well as the more recently evolving 2-dimensional imaging array technology, converts an original document image into digital form, which digital data may then be transferred to a digital printer for output onto a recording medium, such as paper.
While the process of reproducing stacked documents has advanced rapidly, the process of reproducing multiple successive pages of a book or other bound volume of pages has inherent limitations that have prevented comparable advances. A primary limitation of bound document reproduction is the requirement of manual intervention for turning individual pages of the book during the reproduction process. This manual intervention is a significant demand on both manpower and time. With the traditional copier or scanner, stress is applied to the book from the constant handling of the book by the user. The user must repeatedly lift the book from the flat imaging surface and turn the individual book pages, so that subsequent pages or sets of pages may be reproduced. Additional stress is applied to the binding when the book is fully laid open in a substantially flat position against a platen. Furthermore, in an attempt to minimize the amount of distortion that often appears on the reproduced image in the binding region of the pages, the user will often apply yet an additional force to the spine of the book in order to flatten the pages against the imaging surface. These stresses to the book are particularly hazardous to older and/or historical volumes of books.
In order to alleviate the stress applied to the bindings, the platen has been moved to the edge of the cabinet, allowing the book to remain in a relaxed state while being imaged, as illustrated in Smith, U.S. Pat. No. 3,888,584.
Solutions to the manual page turning problem, have looked to automatic page turning mechanisms. Typical of these are:
Berlinsky et al, U.S. Pat. No. 3,484,970, in which a book is laid flat upon a support and an automatic sheet turner using a rotating vacuum head grabs a page and flips it from one side to the other side. Subsequently, a brush follows the path of the roller, sweeping and smoothing out the turned page. PA0 Castagna, U.S. Pat. No. 3,550,296, in which a book is held partially open upon a support and a page turner device, including a suction arm, is used to lift and flip the pages. A constant vacuum force applied through the arm initially causes the page that is to be turned to be lifted. Thereafter, the angular movement of the arm while moving the page to the opposite side of the book, causes the page to disengage from the arm and fall to its respective turned position. PA0 Howard et al, U.S. Pat. No. 4,780,977, in which a book is laid flat upon a support and a page turning apparatus including an arm having a vacuum associated therewith turns the pages. PA0 Nakanishi, U.S. Pat. No. 4,916,839, in which a book is laid flat upon a support and a mechanical means for applying friction to a page to be turned, in combination with air, is used to form a buckle in the page. A sliding plate surface in contact with the buckled page is used to complete the page turning function. PA0 Shinbrot, U.S. Pat. No. 4,663,873, in which an electrostatographic copier incorporates a device for turning pages of an open book. The book is laid flat on a support and an air jet initially separates the pages. A vacuum wheel then picks up the separated page and then flips the page to the opposite side of the book. The book is lowered to turn its pages and is then urged into contact with a glass plate for imaging. PA0 Shinbrot, U.S. Pat. No. 4,673,286 and Garavuso et al, U.S. Pat. No. 4,693,594, in which an electrostatographic copier has a device for turning pages of an open book which is laid flat in a page down position on a moving surface relative to an optical system.
It is also known to provide page turning mechanisms for books in combination with optical systems for capturing the page images. Typical of these are:
In each of these mechanisms (with the exception of Castagna) the book is fully laid open in a substantially flat position. If forced into this position, there is a high likelihood that the binding may be stressed and damaged. Also, in this position, the quality of reproduction may be severely impaired because when the book is laid flat, the bulk in the pages adjacent the binding will lie curved, and not flat, thus distorting the optical depth of field. If the distortion is too great, it is likely that an incomplete image will be formed.
The objects of the present invention are to overcome the problems of the known book imagers and to provide an apparatus which will allow book pages to be reproduced accurately with high resolution, rapidly and automatically, without manual intervention, and with no structural damage to the book itself.